Materials containing triangular structures of magnetic moment are an important pathway to studying unconventional magnetic phenomena that arise from the geometrical frustration. In particular, van-der-Waals (vdW) containing 2D frustrated layers of magnetic moments have been at forefront of studying new materials that can be utilised in creating nano-scale heterostructures and devices. Nb3Br8 is such a vdW compound in which Nb3Br13 clusters form effective spin-1/2 objects that occupy 2D triangular layers. The stacking of these layers changes dramatically at a phase transition near 385K. The low temperature magnetic behaviour indicates a spin-Peierls gap opening, but alternative models exist. We propose to investigate the magnetic ground state, putative spin-Peierls gap and the electron spin dynamics as a function of temperature with positive muons as local magnetic probes.